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February 26th, 2006 at 8:08 pm

Researcher Develops Charcoal-Fired Fuel Cell

University
of Hawai’i researcher Michael Antal has developed a working fuel cell
that uses charcoal as its fuel and operates at bread-baking
temperatures.

The
Antal system, which he calls an aqueous alkali biocarbon fuel cell, is
unlike other fuel cell technology both in that it uses a renewable fuel
and that it does not require particularly high temperatures.

Renewable
energy is the watchword in the modern energy debate, an effort pushed
in large part by high global oil prices and the perception that global
political instability threatens the availability of fuel.

Gov.
Linda Lingle is backing a package of bills in the Legislature that
includes strong support for renewables, and President Bush has been on
the stump in recent weeks on behalf of energy initiatives that include
hydrogen fuel cell cars, solar power, wind research, and more.

Most research today focuses on cells fueled with hydrogen, which must be manufactured— in many cases from fossil fuels.

But "this is effectively a battery that uses charcoal to make electricity," Antal said.

The
technology has attracted interest from around the world, said Dick Cox,
director of the university’s Office of Technology Transfer and Economic
Development.

"I
think it’s a tremendous innovation," Cox said. His office will license
the technology to independent companies, which would pay Antal and the
university for the use of the system.

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Antal’s
cell operates at about 400 degrees Fahrenheit. By contrast, a carbon
cell developed by the Lawrence Livermore National Laboratory operates
at 1,500 degrees.

"People
have been building hydrogen fuel cells for over a century. Our purpose
is to awaken people to the fact that there are new things out there. We
need to think outside the box," Antal said.

The
key to his cell’s operation is the very chemically reactive property of
charcoal, which has a large surface area and burns at relatively low
temperatures, he said.

Antal
said he imagines industrial applications would be most appropriate for
the fuel cell, but figures it might be capable of running an
automobile. Antal’s former associate, University of Tokyo researcher
Kazuhiro Mochidzuki, said the system appears most appropriate for
mid-sized power generation stations.

"Power
generation by carbon fuel cell should not be in so big scale. The
dispersed power system that does not require big generators is suitable
for the carbon fuel cell," Mochidzuki said via e-mail.

Right
now, his lab at the University of Hawai’i is fine-tuning the design,
and looking for companies that would finance the development of a
commercial charcoal fuel cell. Mochidzuki said there are still
technical issues to be resolved.

"Carbon
fuel cell is one of the promising technologies to obtain power from
charcoal at a high efficiency. It can be said that the carbon fuel cell
is an important technology to promote the sustainable biomass energy
system," he said. However, "there are a number of problems to be solved
against its practical use of carbon fuel cell, even if it theoretically
has a good potential."

The
carbon cell functions something like a car battery. It has an anode and
cathode positive- and negative-charged terminals in a liquid solution,
and if you put an electrical load — like a light bulb — between them,
electrical current flows from one to the other. But that’s where the
similarity ends.

In
Antal’s cell, the electrolyte is alkaline potassium hydroxide, not
sulphuric acid. It is kept under pressure to prevent it from boiling
away at 400 degrees. The negative terminal, or cathode, which acts as a
catalyst, is made of nickel and silver or platinum.

The
positive terminal, or anode, is a porous ceramic column filled with
charcoal powder. A piston keeps it pressurized, and serves at the
attachment point for the electrical connection.

In
operation, hydroxide ions in the electrolyte attack the carbon,
creating carbon dioxide and water. The process releases energy.

The cell is fed air to provide the process with new oxygen, and it vents carbon dioxide.

The charcoal does not burn in the sense of a campfire burning. The reaction occurs entirely within the liquid of the fuel cell.

While
fossil-fuel cells also produce carbon dioxide, a greenhouse gas,
charcoal represents a sustainable source of fuel, since the living
plants that produce the charcoal get their carbon by removing carbon
dioxide from the atmosphere.

Antal
said that water-based or aqueous fuel cells have a considerable
history. A hydrogen-based aqueous fuel cell was used in the first
Apollo space mission.

While
his charcoal fuel cell works as it is, Antal said it needs to be more
efficient, and his team is now fine tuning it — working with different
catalysts, different electrolyte strengths and other changes. They also
need to figure out how to continuously feed charcoal fuel to the system.

"Handling
of solid fuel, such as charcoal, is not easy. If we want to feed
charcoal into the cell continuously, we have to solve the problem how
it can be fed. This is one of the biggest problems of solid fuel,"
Mochidzuki said.

Antal,
who holds the University of Hawai’i's Coral Industries Chair of
Renewable Energy Resources, is a longtime advocate of charcoal. Another
of his projects is a flash carbonization reactor, which converts
biomass like macadamia nut shells, wood and grass into charcoal. That
charcoal can be used to cook food, as a filter or, in tandem with the
new fuel cell, as a source of electricity.

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